As the leaves fall there is much revealed in the forest that was hidden just a short time ago, and lichens are a big part of that revelation. Lichens are all around us but they’re one of those things that are so easy to miss unless we happen to be looking for them. Most people seeing this photo would probably say “Oh yes, I see lichens all over the stones in the stone wall.” But what about the tree? That’s a shagbark hickory tree and they have gray, not white bark. The white is a lichen called, appropriately enough, whitewash lichen (Phlyctis argena.) This lichen is usually found on the bark of hardwood trees and is fairly common. It makes the tree look as if it has been painted white, and that’s where its common name comes from. They can be greenish white, silvery, or bright white.
But you wouldn’t have been wrong in pointing out the lichens on the stone wall because it is covered with them, among them rock greenshield lichens (Flavoparmelia baltimorensis.) This lichen always looks like melted candle wax to me. It is very common in this area and is another of those bits of nature that you see so often they no longer register.
Peppered rock shield lichen (Xanthoparmelia conspersa) likes to grow on stone in full sun and I find a lot of them on stone walls like the one pictured in that first photo. They’re a good introduction to lichen study because their brown apothecia, where their spores are produced, are large and easy to see without aid. Lichens are made up of a symbiotic relationship between fungi and algae or cyanobacteria. Technically apothecia are “fungal reproductive structures, in which the fungus reproduces itself through the production of spores” This is not the only way that lichens reproduce, but it is common and the apothecia are often beautiful and well worth watching for.
Another lichen common to stone walls is the sulfur dust lichen (Chrysothrix chlorina.) It’s very yellow and hides under overhangs so it doesn’t get rained on. At least I think that’s why I always find it tucked away like this, but this is odd behavior for a lichen because they usually like a lot of rain and sunshine.
Sulfur dust lichens are kind of granular in texture. If you’re lucky you can sometimes find them with fruiting bodies (apothecia) but more often than not I see them when they aren’t producing spores, like this example.
If you spend time walking along old stone walls eventually you’ll see a stone with a splash of bright orange on it and it will probably be the sidewalk firedot lichen (Caloplaca feracissima,) so called because it is a lime lover and grows on concrete sidewalks, which have lime in them. When you see it in a stone wall it’s a fair bet that the stone it grows on has limestone in it too. This stone looks like granite to me but it is almost completely covered by it.
A closer look at this example of the sidewalk firedot lichen showed it was made up of mostly irregularly shaped fruiting bodies, so it was making plenty of spores. It was raining just a short while before I took this photo so it was also still wet. Lichens are at their best when they are wet because that’s when they’ll show their true colors and size, so that’s when serious lichen hunters look for them. A misty or drizzly day is perfect.
I know of an old stump that has more British soldier lichens (Cladonia cristatella) growing on it than I’ve ever seen in one place. Old rotted logs and stumps are the perfect places to find them and their bright red color makes them relatively easy to spot.
Even I can see this shade of red, and I’m colorblind.
If you see a tree with growths like this on it you really should take a closer look, because there are some amazing things going on here.
One of the things going on in the tree in the previous photo is what is happening on this star rosette lichen (Physcia stellaris.) Its apothecia are a good example of how colors can change, even on the same lichen. This lichen has dark brown apothecia that are often pruinose. Pruinose refers to the white, waxy, powdery coating on the apothecia. You’ve no doubt seen examples of this waxy “bloom” on blueberries and plums. I’ve noticed by watching lichens that have pruinose apothecia that the coating can reflect light in different ways, sometimes appearing gray and at other times more blue, and sometimes even black. The apothecia on this lichen show a range of colors, from brown to light blue. The way the sunlight strikes it has a lot to do with its colors, so sometimes you have to visit a lichen more than once to understand it.
Common goldspeck lichens (Candelariella vitellina) are uncommonly beautiful. Look for this bright yellow crustose lichen on stone, in this case slate. It’s a very artistic lichen and I like the patterns that it makes. I see it on gravestones quite often. It shouldn’t come as a great surprise that, at high magnification, the body of the common goldspeck lichen looks like it’s made up of tiny golden specks. The book Lichens of North America describes the body of this lichen as “little cushions of flattened granules.” This lichen is sometimes sterile, with no fruiting bodies present, as this one appeared to be. Crustose lichens form crusts that tightly adhere to the substrate that they grow on and usually can’t be removed without damaging it.
The golden moonglow lichens (Dimelaena oreina) that I see are usually about an inch across but they can get much bigger. They grow in full sun on granite and don’t seem to change color when they dry out like many other lichens do. The bigger one in the photo was producing spores and that’s something I don’t see this lichen do very often. If you spend much time in cemeteries you have probably seen this pretty lichen, because it seems to like growing on smooth, polished stone, especially granite. It is a another crustose lichen, so removing it from a gravestone would be a challenge. When lichens grow on glass the acids in them can actually etch the glass and this is a problem in the big European cathedrals, especially. I would think the same would be true for polished stone.
Bright yellow-orange poplar sunburst (Xanthomendoza hasseana) is a beautiful lichen with its large disc shaped, sucker like fruiting bodies (apothecia) which are almost always showing. It’s found on tree bark and provides a lot of color in winter when there are no flowers to see. The example shown here was about as big as a penny, or about .75 inches across.
Another sunburst lichen, the elegant sunburst (Xanthoria elegans) was exposed to ultraviolet radiation, cosmic radiation, and the vacuum of space for one and a half years and when it was brought back to earth it grew on as if nothing had happened. Many believe that lichens are virtually indestructible and are therefore as close to immortal as any earth based life form can be.
Pink earth lichen (Dibaeis baeomyces) closely resembles bubblegum lichen (Icmadophila ericetorum.) One of the differences between the two is the length of the stalks that the plump pink apothecia sit on. They are longer on bubblegum lichens than they are on pink earth lichens. Both are very beautiful things that are rarely seen in this area. The whitish or grayish thallus, or body of the lichen, grows on soil; usually on dry acidic soil near blueberry and sweet fern plants. It can sometimes have a bluish cast as well.
Here’s a closer look at the apothecia on the pink earth lichen. You can also see the stalks that support them.
Scattered rock posy lichens (Rhizoplaca subdiscrepans) can be quite small and difficult to see without magnification, but it’s worth looking for them because they almost always have their bright orange apothecia showing. They like to grow on stone, especially granite, in full sun. They don’t seem to change their color when they dry out like many other lichens do. I’ve seen this pretty lichen even on mountain tops.
Some lichens are very easy to identify because there aren’t many others that look like them, and the toadskin lichen is one of those. Toadskin lichens show color changes like many other lichens. When wet it is pliable and pea green and when dry it becomes crisp and ash gray. This example hadn’t completely dried out but it was on its way, even though it had rained that morning. Toadskin lichens get their common name from their many “warts.” They attach themselves to stone at a single point that looks like a belly button, and that makes them an umbilicate lichen. This toadskin is very special, because it is the only one I’ve ever seen that wasn’t on a hill or mountain top. It grows on a boulder at the very water’s edge of a lake and I’m very happy that I found it now that hill climbing is getting more difficult. Now at least I’ll still be able to see these beautiful little things without having to struggle to reach them, if it comes to that.
Smokey eye boulder lichens (Porpidia albocaerulescens) are one of the most beautiful in my opinion, but their beauty is fleeting and it depends on how the light happens to fall on them. If you find one it might not look like this one at all. The pretty golden brown body (thallus) of the lichen is peppered with blue apothecia which again, are colored by the light. Take a look at the next photo to see what a simple change in light can do.
This is the exact same lichen we saw in the previous photo; all that is different is the light, and that’s why if you’re at all interested in lichens you really should visit them at different times of year, as I said when we looked at the star rosette lichen. The previous photo was taken when sunlight was falling on it, and this shot was taken when the lichen was in shade. Not only light but dryness can affect the color of many lichens, so make a note of where you find them and then go back when the weather has changed. I think you’ll be amazed by how much they can change, and also by how beautiful they can be.
There is a low mist in the woods—it is a good day to study lichens. ~Henry David Thoreau
Thanks for coming by.